A The glow-worm belongs to a family of beetles known as the Lampyridae or fireflies. Q30 The fireflies are a huge group containing over 2000 species , with new ones being discovered all the time. The feature which makes fireflies and glow-worms so appealing is their ability to produce an often dazzling display of light. The light is used by the adult fireflies as a signal to attract a mate, and each species must develop its own ‘call-sign’ to avoid being confused with other species glowing nearby. So within any one area each species will differ from its neighbours in some way, for example in the colour or pattern of its light, how long the pulses of light last, the interval between pulses and whether it displays in flight or from the ground.